Lens barrel having an eccentricity adjusting mechanism

Abstract

A lens barrel having an eccentricity adjusting mechanism, the lens barrel includes a first lens frame, a second lens frame, an engaging part, a plate spring, a circumferential direction groove, a guiding groove, a screw hole, a set screw, a tool insertion hole. The first lens frame is disposed in an fixed barrel of the lens barrel, integrally holds a plurality of lenses, and has openings on front and rear end of the first lens frame in an optical axis direction. The second lens frame that holds a part of the plurality of lenses to be subjected to eccentricity adjustment and is inserted from one of the openings to be disposed and held in the first lens frame.

1. A lens barrel having an eccentricity adjusting mechanism, the lens barrel comprising:
 a first lens frame that is disposed in an fixed barrel of the lens barrel, integrally holds a plurality of lenses, and has openings on front and rear end of the first lens frame in an optical axis direction; 
 a second lens frame that holds a part of the plurality of lenses to be subjected to eccentricity adjustment and is inserted from one of the openings to be disposed and held in the first lens frame; 
 an engaging part that is formed on an inner circumferential face of the first lens frame along a circumferential direction of the inner circumferential face and is inwardly projected in a diameter direction so that an inserted side end of the second lens frame or an inserted side end of the lens held in the second lens frame when the second lens frame is inserted from one of the openings into the first lens frame is engaged with the engaging part in the optical axis direction; 
 a plate spring that is mounted in the first lens frame to be in contact with a non-inserted side end of the second lens frame opposite to the inserted side end and press the second lens frame toward the engaging part, the plate spring including a circular part which contacts to the non-inserted side end and a claw part which is outwardly projected in a diameter direction of the circular part from the circular part to be outwardly projected compared to the inner circumferential face of the first lens frame; 
 a circumferential direction groove that is formed on the inner circumferential face of the first lens frame along the circumferential direction toward the outside of the diameter direction, and holds the plate spring mounted in the first lens frame in a manner that the claw part of the plate spring is fitted into the circumferential direction groove so that the plate spring is locked in the optical axis direction; 
 a guiding groove that is formed at a position connected to a circumferential direction end of the circumferential direction groove on the inner circumferential face of the first lens frame in the optical axis direction, and guides the claw part of the plate spring inserted from the one of the openings of the first lens frame to a position where the claw part of the plate spring is fitted into the circumferential direction groove by rotation around the optical axis, 
 a screw hole that penetrates from an outer circumferential face of the first lens frame to the inner circumferential face of the first lens frame at a position of the second lens frame fixed in the first lens frame in the diameter direction; 
 a set screw that is screwed into the screw hole to be in contact with an outer circumferential face of the second lens frame and fix the second lens frame to the first lens frame in the direction orthogonal to the optical axis, an eccentricity adjustment for the lens held in the second lens frame is performed by adjusting an insertion amount of the set screw into the screw hole to adjust a fixing position of the second lens frame, and 
 a tool insertion hole that is formed to penetrate from the outside of the fixed barrel to the screw hole, a tool for adjusting the insertion amount being inserted into the tool insertion hole. 
 
     
     
       2. The lens barrel having the eccentricity adjusting mechanism according to  claim 1 , wherein the screw hole is formed on at least three positions along the circumferential direction of the first lens frame. 
     
     
       3. The lens barrel having the eccentricity adjusting mechanism according to  claim 1 , wherein the circumferential direction groove is formed on a position intersecting with a plane surface including the position of the screw hole, among plane surfaces having the optical axis as their end sides. 
     
     
       4. The lens barrel having the eccentricity adjusting mechanism according to  claim 1 , wherein the lens group held in the first lens frame is positioned at the insertion opening side compared to the lenses held in the second lens frame, and has an aperture side lens having a larger diameter than the outer circumference of the second lens frame,
 the opening side lens is held at a position of an enlarged diameter inner circumferential face having an enlarged diameter compared to the inner circumferential face of the second lens frame in which the circumferential direction groove is formed, and 
 the optical axis direction of the opening side lens is positioned by a wall surface of a step-difference portion between the inner circumferential surface, in which the second lens frame is contained and held, and the enlarged diameter inner circumferential face. 
 
     
     
       5. The lens barrel having the eccentricity adjusting mechanism according to  claim 4 , wherein the opening side lens is held in the first lens frame so that an interval ring is disposed between the opening side lens and the wall face. 
     
     
       6. The lens barrel having the eccentricity adjusting mechanism according to  claim 1 , wherein the lens group is a rear master lens group among optical systems disposed in the fixed barrel.